Less salmon stocked in Lake Michigan

March 31, 2006

MUSKEGON, Mich. (AP) -- Although charter-boat anglers caught a near-record amount of chinook salmon last year in Lake Michigan, the four states surrounding the lake have agreed to stock it with 25 percent less chinook this year in an effort to help prevent the fish from eating themselves into oblivion. No one knows whether the biological experiment -- aimed at propping up the lake's supply of alewife, the small fish that chinook salmon eat almost exclusively -- will work. "This may do the trick and the alewife will come back, or the alewife might not come back and we'll still have these (biological) red flags," said Jay Wesley, the southern Lake Michigan unit manager for the Michigan Department of Natural Resources. Among the red flags evident to salmon anglers last year was that the fish they caught were much smaller than in the past, according to state data. Charter anglers in Lake Michigan caught only four chinook last year that were worthy of a Master Angler award, meaning the fish weighed at least 27 pounds or measured at least 41 inches long. In 1999, the state handed out 153 of the awards for chinook caught in the lake, according to state records. Alewife rely heavily on diporeia, a tiny, shrimp-like creature that lives on the lake's bottom. A decline in diporeia -- blamed on the Great Lakes invasion of zebra mussels -- has shrunk the size of the lake's alewife, which, in turn, has made the chinook salmon smaller. Because the alewife are smaller, a chinook living in the lake must consume 22 percent more of the fish than in the 1980s to get the same nutritional benefit, according to a study in the current issue of the Canadian Journal of Fisheries and Aquatic Sciences. The reduced salmon stocking levels in Lake Michigan will take place this spring and continue until the alewife population rebounds, Wesley told The Muskegon Chronicle for a story published Monday. Scientists won't know before this fall whether the alewife population is responding favorably to having fewer salmon in the lake. The changes in Lake Michigan's diporeia, alewife and chinook populations bear striking similarities to the changes experienced in Lake Huron before its alewife population began to plummet in 2002. Huron's salmon fishery virtually disappeared shortly after the alewife vanished, according to government data.Information from: The Muskegon Chronicle, http://www.mlive.com/muchronicle